This invention relates generally to the bundling of envelopes, and more particularly, is directed to apparatus for automatically banding a stack of envelopes.
In order to reduce mailing costs, for example, for bulk rate mail, the U.S. Post Office requires that stacks of envelopes be sorted as to zip code and bundled. For a large mailing, these envelopes can easily be sorted and/or printed in accordance with the zip codes so as to sort the same. However, bundling of the stacks of envelopes has generally been performed manually by stretching rubber bands about the stacks of envelopes. This, however, is disadvantageous for two reasons. First, the manual stretching of rubber bands about the stacks of envelopes takes considerable time and labor, and is therefore cost inefficient. Secondly, the conventional rubber bands that are used tend to bite into the edges of the envelopes, oftentimes tearing the same. In addition, those persons who used conventional rubber bands frequently complained of carpal tunnel syndrome.
There are presently some machines that perform such banding operations. However, such machines are very slow and therefore also cost inefficient. Specifically, such machines are tie machines in which the stack of envelopes is rotated so that the tie can be made in two transverse directions. Further, the tie used is twine or polyester rope which bites into the edge of the envelopes. Strapping machines have also been used with a nylone strap. However, such strap is a relatively stiff material that tends to damage the envelopes and envelopes bundled in this manner are not acceptable to the U.S. Post Office.